Methods and arrangements for traffic indication mapping in wireless networks

ABSTRACT

Embodiments may implement a new hierarchical data structure for traffic indication mapping to facilitate transmissions for wireless communications devices. Many embodiments comprise MAC sublayer logic to generate and transmit management frames such as beacon frames with a partial virtual bitmap based upon the hierarchical data structure for traffic indication mapping. In some embodiments, the MAC sublayer logic may store the traffic indication map and/or the traffic indication map structure in memory, in logic, or in another manner that facilitates transmission of the frames. Some embodiments may receive, detect, and decode communications with frames comprising the partial virtual bitmap based upon the hierarchical data structure. In some embodiments, indications of buffered data for pages, super-blocks, blocks, sub-blocks, and/or stations may be inverted. In several embodiments, a new association identifier (AID) structure is defined for the new hierarchical data structure for traffic indication mapping.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/977,703, filed Mar. 19, 2014, which is in turn a non-provisionalapplication deriving its priority date from provisional application61/544,883, filed Oct. 7, 2011. This application therefore claimspriority to Oct. 7, 2011.

BACKGROUND

Embodiments are in the field of wireless communications. Moreparticularly, embodiments are in the field of communications protocolsbetween wireless transmitters and receivers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an embodiment of a wireless network comprising aplurality of communications devices, including multiple fixed or mobilecommunications devices;

FIG. 1A depicts an embodiment of a hierarchical data structure fortraffic indication mapping;

FIG. 1B depicts an embodiment of an association identifier structure forthe hierarchical data structure illustrated in FIG. 1A;

FIG. 1C depicts an embodiment of a management frame with a trafficindication map element for establishing communications between wirelesscommunication devices;

FIG. 1D depicts an embodiment of a traffic indication map element forestablishing communications between wireless communication devices;

FIG. 1E depicts an embodiment of partial virtual bitmap based upon ahierarchical data structure for traffic indication mapping such as thehierarchical data structure illustrated in FIG. 1A;

FIG. 1F depicts an embodiment of a traffic indication map, virtualbitmap control field such as the traffic indication map, virtual bitmapcontrol field illustrated in FIG. 1D;

FIG. 1G depicts an embodiment of a block field such as the block fieldsillustrated in FIG. 1E;

FIG. 1H depicts an embodiment of partial virtual bitmap based upon ahierarchical data structure for traffic indication mapping such as thehierarchical data structure illustrated in FIG. 1A with example valuesin each field;

FIG. 2 depicts an embodiment of an apparatus to generate, transmit,receive and interpret a frame with a partial virtual bitmap based upon ahierarchical data structure for traffic indication mapping;

FIG. 3 depicts an embodiment of a flowchart to generate a frame with apartial virtual bitmap based upon a hierarchical data structure fortraffic indication mapping;

FIGS. 4A-B depict embodiments of flowcharts to transmit, receive, andinterpret communications with frames having partial virtual bitmapsbased upon a hierarchical data structure for traffic indication mappingas illustrated in FIG. 2; and

FIG. 5 depicts an embodiment of a flowchart to decode a frame with apartial virtual bitmap based upon a hierarchical data structure fortraffic indication mapping.

DETAILED DESCRIPTION OF EMBODIMENTS

The following is a detailed description of novel embodiments depicted inthe accompanying drawings. However, the amount of detail offered is notintended to limit anticipated variations of the described embodiments;on the contrary, the claims and detailed description are to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the present teachings as defined by the appended claims.The detailed descriptions below are designed to make such embodimentsunderstandable to a person having ordinary skill in the art.

References to “one embodiment,” “an embodiment,” “example embodiment,”“various embodiments,” etc., indicate that the embodiment(s) of theinvention so described may include a particular feature, structure, orcharacteristic, but not every embodiment necessarily includes theparticular feature, structure, or characteristic. Further, repeated useof the phrase “in one embodiment” does not necessarily refer to the sameembodiment, although it may.

As used herein, unless otherwise specified the use of the ordinaladjectives “first,” “second,” “third,” etc., to describe a commonobject, merely indicate that different instances of like objects arebeing referred to, and are not intended to imply that the objects sodescribed must be in a given sequence, either temporally, spatially, inranking, or in any other manner.

Embodiments may implement a new hierarchical data structure for trafficindication mapping to facilitate transmissions for wirelesscommunications devices. Many embodiments comprise MAC sublayer logic togenerate and transmit management frames such as beacon frames with apartial virtual bitmap based upon the hierarchical data structure fortraffic indication mapping. In some embodiments, the MAC sublayer logicmay store the traffic indication map and/or the traffic indication mapstructure in memory, in logic, or in another manner that facilitatestransmission of the frames. Some embodiments may receive, detect, anddecode communications with frames comprising the partial virtual bitmapbased upon the hierarchical data structure.

In many embodiments, the new hierarchical data structure for trafficindication mapping may describe stations assigned to a sub-block, morethan one sub-blocks of stations assigned to a blocks, more than oneblocks of stations assigned to a super-block, and more than onesuper-blocks of stations assigned to a page of more than one pages ofstations. In one embodiment, the new hierarchical data structure fortraffic indication mapping comprises four pages to facilitate mappingfor up to 2048 stations per page. In such embodiments, each page maycomprise four super-blocks with unique subsets of the stations assignedto the page, each super-block may comprise eight blocks of uniquesubsets of the stations assigned to the super-block, each block maycomprise eight sub-blocks of unique subsets of the stations assigned tothe block, and each sub-block may comprise a unique subset of eightstations. Furthermore, the partial virtual bitmaps that refer to suchstructures may identify the association identifiers for stations forwhich data is being buffered by an access point (AP) by identifying thecorresponding page(s), super-block(s), block(s), and sub-blocks withinwhich the stations reside. In many embodiments, the AP may determine andtransmit such an association identifier to each station as the stationsare associated with the AP.

In many embodiments, the AP may compress and/or reduce the amount ofdata in the partial virtual bitmap of the traffic indication map (TIM)element. In some embodiments, the amount of data may bereduce/compressed by referencing the blocks and/or sub-blocks in bitmapsand including or excluding the blocks and/or sub-blocks within thepartial virtual bitmap based upon the content of the blocks and/orsub-blocks. In some embodiments, the amount of data may bereduce/compressed by limiting the range of blocks within the partialvirtual bitmap based upon the page to which the blocks are assignedand/or the block indexes.

In some embodiments, indications of buffered data for pages,super-blocks, blocks, sub-blocks, and/or stations may be inverted. Inmany embodiments, inverting such indications may compress the datatransmitted in the TIM element. For instance, if the number of blocksthat comprise all logical ones exceeds the number of blocks with alllogical zeros, less data may be transmitted in the TIM element todescribe the stations with all logical zeros. Thus, the indications ofbuffered data for the stations may be inverted by, e.g., inverting a bitin the block control field, allowing stations described in the TIMelement to indicate that such stations do not have buffered data insteadof including, in the TIM element, stations that do have buffered data.

In several embodiments, a new association identifier (AID) structure isdefined for the new hierarchical data structure for traffic indicationmapping. In many embodiments, the new AID structure comprises bitsidentifying a page, bits identifying a super-block, bits identifying ablock, bits identifying a sub-block, and bits identifying a stationwithin the particular sub-block. A station associated with an AP mayparse the association identifier to determine the page, super-block,block, sub-block, and bit position within that sub-block of a TIMelement that identifies whether the AP is buffering data for thestation.

Some embodiments implement Institute of Electrical and ElectronicEngineers (IEEE) 802.11 systems such as IEEE 802.11ah systems and othersystems that operate in accordance with standards such as the IEEE802.11-2007, IEEE Standard for Information technology—Telecommunicationsand information exchange between systems—Local and metropolitan areanetworks—Specific requirements—Part 11: Wireless LAN Medium AccessControl (MAC) and Physical Layer (PHY) Specifications(http://standards.ieee.org/getieee802/download/802.11-2007.pdf).

According to one embodiment, the partial virtual bitmap based upon thehierarchical data structure for traffic indication mapping is defined toenable a greater number of associated stations and to utilize a moreefficient TIM element and, in many instances, smaller TIM element forlow-power consumption stations such as small battery-powered wirelessdevices (e.g., sensors) to use Wi-Fi to connect to the Internet withvery low power consumption. Supporting such a large number of stationsbecomes challenging especially when those associated stations are in apower save (PS) mode because a much larger TIM element may have to betransmitted to describe, in a partial virtual map, all stations betweenthe block with the lowest station AID for which data is buffered to theblock with the highest station AID. Since IEEE 802.11ah is expected tohave a physical layer (PHY) data rate of 1/10 or lower compared to802.11n PHY data rates, the overhead of TIM element transmission becomesmuch larger in terms of channel occupancy.

Several embodiments comprise access points (APs) for and/or clientdevices of APs or stations (STAB) such as routers, switches, servers,workstations, netbooks, mobile devices (Laptop, Smart Phone, Tablet, andthe like), as well as sensors, meters, controls, instruments, monitors,appliances, and the like. Some embodiments may provide, e.g., indoorand/or outdoor “smart” grid and sensor services. For example, someembodiments may provide a metering station to collect data from sensorsthat meter the usage of electricity, water, gas, and/or other utilitiesfor a home or homes within a particular area and wirelessly transmit theusage of these services to a meter substation. Further embodiments maycollect data from sensors for home healthcare, clinics, or hospitals formonitoring healthcare related events and vital signs for patients suchas fall detection, pill bottle monitoring, weight monitoring, sleepapnea, blood sugar levels, heart rhythms, and the like. Embodimentsdesigned for such services may generally require much lower data ratesand much lower (ultra low) power consumption than devices provided inIEEE 802.11n/ac systems.

Logic, modules, devices, and interfaces herein described may performfunctions that may be implemented in hardware and/or code. Hardwareand/or code may comprise software, firmware, microcode, processors,state machines, chipsets, or combinations thereof designed to accomplishthe functionality.

Embodiments may facilitate wireless communications. Some embodiments maycomprise low power wireless communications like Bluetooth®, wirelesslocal area networks (WLANs), wireless metropolitan area networks(WMANs), wireless personal area networks (WPAN), cellular networks,communications in networks, messaging systems, and smart-devices tofacilitate interaction between such devices. Furthermore, some wirelessembodiments may incorporate a single antenna while other embodiments mayemploy multiple antennas. For instance, multiple-input andmultiple-output (MIMO) is the use of radio channels carrying signals viamultiple antennas at both the transmitter and receiver to improvecommunication performance.

While some of the specific embodiments described below will referencethe embodiments with specific configurations, those of skill in the artwill realize that embodiments of the present disclosure mayadvantageously be implemented with other configurations with similarissues or problems.

Turning now to FIG. 1, there is shown an embodiment of a wirelesscommunication system 1000. The wireless communication system 1000comprises a communications device 1010 that may be wire line andwirelessly connected to a network 1005. The communications device 1010may communicate wirelessly with a plurality of communication devices1030, 1050, and 1055 via the network 1005. The communications device1010 may comprise an access point. The communications device 1030 maycomprise a low power communications device such as a sensor, a consumerelectronics device, a personal mobile device, or the like. Andcommunications devices 1050 and 1055 may comprise sensors, stations,access points, hubs, switches, routers, computers, laptops, netbooks,cellular phones, smart phones, PDAs (Personal Digital Assistants), orother wireless-capable devices. Thus, communications devices may bemobile or fixed. For example, the communications device 1010 maycomprise a metering substation for water consumption within aneighborhood of homes. Each of the homes within the neighborhood maycomprise a sensor such as the communications device 1030 and thecommunications device 1030 may be integrated with or coupled to a waterusage meter.

Initially, the communications device 1030 may associate with thecommunications device 1010 and receive an association identifier (AID)from the communications device 1010 to uniquely identify thecommunications device 1030 with respect to other communications devicesassociated with the communications device 1010. In many embodiments, theAID may comprise 13 bits, wherein the bits identify the page,super-block, block, sub-block, and a bit position for the station withinthe sub-block. FIG. 1B depicts an embodiment of such an AID structure1150. Thereafter, the communications device 1010 may buffer data such asmedium access control (MAC) service data units (MSDUs) for thecommunications device 1030.

After buffering an MSDU for the communications device 1030, thecommunications device 1010 may transmit a beacon to associated devices,identifying the devices with data buffered by the communications device1010 by means of a traffic indication map (TIM) element such as theframe 1014. In the present embodiment, the TIM element may identify theAID of each station that has data buffered such as the communicationsdevice 1030 by identifying the page, super-block, block, and sub-blockof the stations. The TIM element may also comprise a number of bits suchas eight bits that identify the stations in the sub-block that havebuffered data via logical ones and zeroes. In many embodiments, alogical one at the bit location in the sub-block associated with thecommunications device 1030 may indicate that the communications device1010 is buffering data for the communications device 1030. In furtherembodiments, a logical zero may represent that the communications device1010 is buffering data for the communications device 1030.

The communications device 1030 may interpret the TIM element based uponthe association identifier assigned to the communications device 1030 bythe communications device 1010. In many embodiments, the communicationsdevice 1030 may parse the association identifier to determine a pageassociated with communications device 1030 and may parse the TIM elementto determine if the TIM element describes data buffering for stationsassociated with the same page. If so, the communications device 1030 mayrepeat the process of parsing the association identifier and comparingthe values of the super-block, block, and sub-block with thoserepresented by the TIM element to determine whether the TIM elementindicates that the communications device 1010 is buffering data for thecommunications device 1030 and/or whether the TIM element includes dataat the bit position in the sub-block associated with the communicationsdevice 1030 that indicates that the communications device 1010 isbuffering data for the communications device 1030.

In further embodiments, the communications device 1010 may facilitatedata offloading. For example, communications devices that are low powersensors may include a data offloading scheme to, e.g., communicate viaWi-Fi, another communications device, a cellular network, or the likefor the purposes of reducing power consumption consumed in waiting foraccess to, e.g., a metering station and/or increasing availability ofbandwidth. Communications devices that receive data from sensors such asmetering stations may include a data offloading scheme to, e.g.,communicate via Wi-Fi, another communications device, a cellularnetwork, or the like for the purposes of reducing congestion of thenetwork 1005.

The network 1005 may represent an interconnection of a number ofnetworks. For instance, the network 1005 may couple with a wide areanetwork such as the Internet or an intranet and may interconnect localdevices wired or wirelessly interconnected via one or more hubs,routers, or switches. In the present embodiment, network 1005communicatively couples communications devices 1010, 1030, 1050, and1055.

The communication devices 1010 and 1030 comprise memory 1011 and 1031,medium access control (MAC) sublayer logic 1018 and 1038, and physicallayer (PHY) logic 1019 and 1039, respectively. The memory 1011 and 1031may comprise a storage medium such as dynamic random access memory(DRAM), read only memory (ROM), buffers, registers, cache, flash memory,hard disk drives, solid-state drives, or the like. The memory 1011 and1031 may store frames and/or frame structures, or portions thereof suchas a management frame structure and a traffic indication map (TIM)element based upon a hierarchical data structure such as thehierarchical data structure 1100 illustrated in FIG. 1A. Furthermore,the memory 1011 and 1031 may comprise a traffic indication map in ahierarchical data structure that identifies the associated stations forwhich data is buffered. For example, the memory 1011 may comprise anindication that the communications device 1010 comprises buffered dataas well as a reference or link to the buffered data for thecommunications device 1030.

The MAC sublayer logic 1018, 1038 may comprise logic to implementfunctionality of the MAC sublayer of the data link layer of thecommunications device 1010, 1030. The MAC sublayer logic 1018, 1038 maygenerate the frames such as management frames and the physical layerlogic 1019, 1039 may generate physical layer protocol data units (PPDUs)based upon the frames. For example, the frame builder 1013 may generateframes with a TIM element 1014 and the data unit builder of the physicallayer logic 1019 may encapsulate the frames with preambles to generatePPDUs for transmission via a physical layer device such as thetransceivers (RX/TX) 1020 and 1040.

The frame with the TIM element 1014 may comprise a frame such as themanagement frame 1200 in FIG. 1C. In particular, the frame with the TIMelement 1014 may comprise a partial virtual bitmap based upon ahierarchical data structure such as the partial virtual bitmap 1700illustrated in FIG. 1E and may identify each station within, e.g., onepage, that has data buffered by an AP such as communications device1010. For example, the AP may not arbitrarily transmit MSDUs to stationsoperating in a power saving (PS) mode, but may buffer the MSDUs and onlytransmit the MSDUs at designated times. Furthermore, the stations thatcurrently have buffered MSDUs within the AP may be identified in framecomprising a TIM element, which may be included, e.g., as an elementwithin beacon frames generated by the AP. Then, each station maydetermine that an MSDU is buffered for the station (such ascommunications device 1030) by receiving and interpreting the TIMelement in the beacon frame. The station may interpret the TIM elementby determining whether the page including their AID is included in theTIM element, determining whether the super-block including their AID isincluded in the element, determining whether the block with their AID isincluded in the TIM element, determining whether the sub-block withtheir AID is included in the TIM element, and, if, so, determiningwhether the bit associated with their AID indicates that data is beingbuffered at the AP. In a base service set (BSS) operating under adistributed coordination function (DCF), upon determining that an MSDUis currently buffered in the AP, a station operating in the PS mode maytransmit a PS-Poll frame to the AP, which may respond with thecorresponding buffered MSDU immediately, or acknowledge the PS-Poll andrespond with the corresponding MSDU at a later time.

The communications devices 1010, 1030, 1050, and 1055 may each comprisea transceiver such as transceivers 1020 and 1040. Each transceiver 1020,1040 comprises an RF transmitter and an RF receiver. Each RF transmitterimpresses digital data onto an RF frequency for transmission of the databy electromagnetic radiation. An RF receiver receives electromagneticenergy at an RF frequency and extracts the digital data therefrom.

FIG. 1 may depict a number of different embodiments including aMultiple-Input, Multiple-Output (MIMO) system with, e.g., four spatialstreams, and may depict degenerate systems in which one or more of thecommunications devices 1010, 1030, 1050, and 1055 comprise a receiverand/or a transmitter with a single antenna including a Single-Input,Single Output (SISO) system, a Single-Input, Multiple Output (SIMO)system, and a Multiple-Input, Single Output (MISO) system.

In many embodiments, transceivers 1020 and 1040 implement orthogonalfrequency-division multiplexing (OFDM). OFDM is a method of encodingdigital data on multiple carrier frequencies. OFDM is afrequency-division multiplexing scheme used as a digital multi-earnermodulation method. A large number of closely spaced orthogonalsub-carrier signals are used to carry data. The data is divided intoseveral parallel data streams or channels, one for each sub-carrier.Each sub-carrier is modulated with a modulation scheme at a low symbolrate, maintaining total data rates similar to conventionalsingle-carrier modulation schemes in the same bandwidth.

An OFDM system uses several carriers, or “tones,” for functionsincluding data, pilot, guard, and nulling. Data tones are used totransfer information between the transmitter and receiver via one of thechannels. Pilot tones are used to maintain the channels, and may provideinformation about time/frequency and channel tracking. Guard tones maybe inserted between symbols such as the short training field (STF) andlong training field (LTF) symbols during transmission to avoidinter-symbol interference (ISI), which might result from multi-pathdistortion. These guard tones also help the signal conform to a spectralmask. The nulling of the direct component (DC) may be used to simplifydirect conversion receiver designs.

In some embodiments, the communications device 1010 optionally comprisesa Digital Beam Former (DBF) 1022, as indicated by the dashed lines. TheDBF 1022 transforms information signals into signals to be applied toelements of an antenna array 1024. The antenna array 1024 is an array ofindividual, separately excitable antenna elements. The signals appliedto the elements of the antenna array 1024 cause the antenna array 1024to radiate one to four spatial channels. Each spatial channel so formedmay carry information to one or more of the communications devices 1030,1050, and 1055. Similarly, the communications device 1030 comprises atransceiver 1040 to receive and transmit signals from and to thecommunications device 1010. The transceiver 1040 may comprise an antennaarray 1044 and, optionally, a DBF 1042.

FIG. 1A depicts an embodiment of a hierarchical data structure 1100 fortraffic indication mapping. On the top level of the hierarchy, thetraffic indication virtual map may be divided into four pages. Each pagemay support up to 2048 stations and, in several embodiments, each pagemay be transmitted as a separate TIM element. In some embodiments,multiple TIM elements may be transmitted in the same medium accesscontrol (MAC) service data unit (MSDU). In further embodiments, multipleMSDUs may be aggregated in each physical layer (PHY) protocol data units(PPDUs). In other embodiments, the hierarchical data structure 1100 maycomprise more or less than four pages.

Each page may comprise four super-blocks and each of the foursuper-blocks may support up to 512 of the stations associated with thecorresponding page. In further embodiments, each super-block maycomprise more or less than four super-blocks.

Each super-block may comprise eight blocks and each of the eight blocksmay support up to 64 of the stations associated with the correspondingsuper-block. In further embodiments, each super-block may comprise moreor less than eight blocks.

Each block may comprise eight sub-blocks. Each sub-block may be oneoctet in length and may support eight of the stations associated withthe corresponding block. In further embodiments, each block may comprisemore or less than eight sub-blocks and each of the sub-blocks may bemore or less than one octet in length.

Each bit of a sub-block may correspond to a different associationidentifier (AID) and thus, each bit may uniquely identify a station. Inthe present embodiment, the bit may be set to 1 if there is databuffered at the AP. Otherwise, the bit may be cleared to 0.

FIG. 1B depicts an embodiment of an association identifier structure1150 for the hierarchical data structure illustrated in FIG. 1A. In thepresent embodiment, the AID comprises 13 bits. In other embodiments, theAID structure 1150 may comprise more or less than 13 bits.

In the present embodiment, the AID structure 1150 may comprise a pageidentifier (ID) having two bits (b12-b11), which is represented as “a”in the AID equation depicted below the AID structure 1150. The AIDstructure 1150 may comprise a super-block index having two bits(b10-b9), which is represented as “b” in the AID equation. The AIDstructure 1150 may comprise a block index having three bits (b8-b6),which is represented as “c” in the AID equation. The AID structure 1150may comprise a sub-block index having three bits (b5-b3), which isrepresented as “d” in the AID equation. And, the AID structure 1150 maycomprise a station bit position index having three bits (b2-b0), whichis represented as “e” in the AID equation.

The AID equation may describe the calculation of a unique number perstation based upon the hierarchical data structure illustrated in FIG.1A. In particular, the AID unique number in this embodiment may becalculated by the following formula:AID=((((Page ID×4+(Super-block index−1))×8+(Block index−1))×8+(Sub-blockindex−1))×8+(station bit position index)

To illustrate, refer to FIG. 1E at super-block 1, block 2, sub-block 6,and station 4. The variables are: the Page ID=0, the super-blockindex=1, the block index=2, the sub-block index=6. As a result, theequation becomes:AID=((((0×4+(1−1))×8+(2−1))×8+(6−1))×8+(4)=108

FIG. 1C depicts an embodiment of a management frame 1200 forcommunications between wireless communication devices such ascommunications devices 1010, 1030, 1050, and 1055 in FIG. 1. Themanagement frame 1200 may comprise a MAC header 1201, a frame body 1214,and a frame check sequence (FCS) field 1226. The MAC header 1201 maycomprise the frame control field 1202 and other MAC header fields 1208.The frame control field 1202 may be two octets and may identify the typeand subtype of the frame such as a management type and, e.g., a beaconframe subtype. The other MAC header fields 1208 may comprise, forexample, one or more address fields, identification fields, controlfields, or the like.

In some embodiments, the management frame 1200 may comprise a frame body1214. The frame body 1214 may be a variable number of octets and mayinclude data elements, control elements, or parameters and capabilities.In the present embodiment, the frame body 1214 comprises a trafficindication map (TIM) element 1220.

FIG. 1D illustrates an embodiment of a TIM element 1300. An access point(AP) may transmit the TIM element 1300 to inform stations such as lowpower sensors that the AP is buffering data for the station. In manyembodiments, the station may then initiate communications with the AP toobtain the buffered data such as via a poll frame. In other embodiments,the AP may transmit the data to the station after transmitting thebeacon.

The TIM element 1300 may comprise fields such as an element identifier(ID) field 1302, a length field 1306, a delivery TIM (DTIM) count field1308, a DTIM period field 1310, a TIM virtual bitmap control field 1312,and partial virtual bitmap 1314. The element ID field 1302 may be oneoctet and may identify the element as a TIM element 1300. The lengthfield 1306 may be one octet and may define the length of the TIM element1300 or the length of a portion thereof. The DTIM count 1308 may be oneoctet and may indicate how many beacon frames (including the currentframe) appear before the next DTIM frame. A DTIM Count field 1308 valueof 0 may indicate that the current TIM frame is a DTIM frame. Forinstance, immediately after every DTIM (beacon frame with DTIM Countfield 1308 of the TIM element 1300 equal to zero), the AP shall transmitall buffered, group-addressed frames. If the TIM indicating the bufferedMSDU or aggregate MSDU (A-MSDU) is sent during a contention-free period(CFP), a contention-free (CF)-Pollable station operating in thepower-savings (PS) mode does not send a power-saving (PS)-Poll frame,but remains active until the buffered MSDU or A-MSDU is received (or theCFP ends). If any station in its base service set (BSS) is in PS mode,the AP may buffer all group-addressed MSDUs and deliver them to allstations immediately following the next beacon frame containing a DTIMtransmission.

The DTIM period field 1310 may be one octet and may indicate the numberof beacon intervals between successive DTIMs. In many embodiments, ifall TIM frames are DTIMs, the DTIM period field 1310 may have the value1.

The TIM virtual bitmap control field 1312 may be one octet and maydescribe the content of the partial virtual bitmap 1314. For instance,the TIM virtual bitmap may include a bit such as bit 0 that contains atraffic indicator bit associated with AID 0. This bit may be set to 1 inTIM elements 1300 with a value of 0 in the DTIM Count field 1308 whenone or more group-addressed frames are buffered at the AP. In someembodiments, the TIM virtual bitmap control field 1312 may include aninversion bit to invert the indications of data buffered in the partialvirtual bitmap such as in super-blocks, blocks, and sub-blocks, toinclude indications that data is not buffered for such stations.

An embodiment of a TIM virtual partial bitmap control field 1500 isdepicted in FIG. 1F. The TIM virtual partial bitmap control field 1500may comprise a page identifier (ID) field 1504, a reserved field 1506,and a super-block bitmap field 1508. The page ID field 1504 may be 2bits in length and may indicate the page index of 0 through 3 (binarybits 00, 01, 10, and 11, respectively) to represent four pages. Thereserved field 1506 may be two bits and may be used for differentfunctions. One such function may comprise extending the presentembodiment to include more than four pages. For instance, the reservedfield 1506 may extend the page ID field 1506 to describe eight or 16pages rather than four pages.

The super-block bitmap field 1508 may be four bits in length and mayindicate which super-block is present in the following partial virtualbitmap 1314 in a block bitmap field such as a block bitmap field 1708illustrated in FIG. 1E. The four bits in the super-block bitmap field1508 may correspond to four super-blocks. If the n-th bit in the fieldis set to 1, then the n-th super-block may be present in the blockbitmap field 1708. Otherwise, the n-th super-block may not be present inthe block bitmap field 1708. Looking to the embodiment 1800 illustratedin FIG. 1H, only the first two super-blocks (super-blocks 1 and 2) willbe present in the partial virtual bitmap 1700 because the valuesassociated with super-blocks 1 and 2 are ones and the values associatedwith super-blocks 3 and 4 are zeros, “1100”, in the super-block bitmapfield. Therefore, for this embodiment, the super-block bitmap 1508 isencoded as “1100” and the block bitmap field 1708 will be two octets inlength. In other situations, the super-block bitmap field 1508 may beencoded as “1110” and the block bitmap field 1708 will be three octetsin length or the super-block bitmap field 1508 may be encoded as “1111”and the block bitmap field 1708 will be four octets in length.

Referring again to FIG. 1D, the partial virtual bitmap field 1314 maycomprise bits describing stations for which data is buffered by the APbased upon a hierarchical data structure such as the hierarchical datastructure illustrated in FIG. 1A. FIG. 1E depicts an embodiment of apartial virtual bitmap field 1700. The partial virtual bitmap 1700 maycomprise the block bitmap field 1708 and a variable number of blocksfrom block 1 1710 to block N 1712.

In the present embodiment, the block bitmap field 1708, if present, isvariable in length (1 to 4 octets) depending on the encoding ofsuper-block bitmap such as the super-block bitmap field 1508 in FIG. 1F.If the super-block bitmap field 1508 value is 0000, then the blockbitmap field 1708 is not present. The block bitmap field 1708 mayindicate which blocks (1 through N) are present in the following blockfields 1710 through 1712. The m-th bit in the block bitmap field 1708indicates the m-th block. If the m-th bit is set to 1, the m-th block ispresent in the following block fields 1710 through 1712. If the m-th bitis set to 0, the m-th block is not present in the following block fields1710 through 1712.

To illustrate, refer to the embodiment 1800 in FIG. 1H. In theembodiment 1800, the block bitmap 1708 only comprises non-zero valuesfor block 1, block 2, and block 16 and the other blocks are all zeros sothe encoded value of the block bitmap field 1708 is “1100 0000 00000001” and is two octets in length. Furthermore, there will be threeblock fields (block 1, block 2, and block 16) following the block bitmapfield 1708 in the embodiment 1800.

According to an embodiment, to further improve the efficiency, one bitof the reserved field 1506 can be used as a block bitmap control bit toindicate whether the block bitmap field 1708 is present or not followingthe super-block bitmap field 1508. If all the blocks are present, theblock bitmap field 1708 can be removed since all the bits will be set toones. Therefore, if the block bitmap control bit is set to 1, the blockbitmap field 1708 is not present but all the blocks 1 through N arepresent. If the block bitmap control bit is cleared to 0, the blockbitmap field 1708 is present.

In other embodiments, one or more bits of, e.g., the block bitmap field1708 and/or the reserved field 1506 may indicate that values of bits forstations having buffered data at the AP have been inversed. In many suchembodiments, the inversion process may increase the efficiency of theTIM element 1300 by reducing the amount of data to transmit to areceiving station to communicate the TIM element.

Each block field such as block fields 1 1710 through N 1712, if present,may comprise a variable in length of, e.g., 1 to 9 octets and maycomprise a block control field and sub-block bitmap fields 1 1608through N 1610.

Referring now to FIG. 1G, there is shown an embodiment of a block field1600 such as the block field 1 1710 through block field N 1712illustrated in the partial virtual bitmap field 1700. The block field1600 comprises a block control field 1604 and possibly sub-block bitmap1 1608 through sub-block bitmap N 1610.

The block control field 1604 may be one octet in length and each bitindicates which sub-block is present in the following sub-block bitmaps1 1608 through sub-block bitmap N 1610, each also being one octet inlength. If the 1-th bit in the block control field 1604 is set to 1, the1-th sub-block bitmap is present in the following sub-block bitmaps. Ifthe 1-th bit in the block control field 1604 is set to 0, the 1-thsub-block bitmap is not present in the following sub-block bitmaps.Looking at the embodiment 1800 shown in FIG. 1H, for block 1 ofsuper-block 1, the block control field 1604 is encoded as “10100100” andis followed by three sub-blocks, sub-block 1, sub-block 3, and sub-block6. Similarly, for block 2 of super-block 1, the block control field isencoded as “00000100” and is followed by sub-block 6 and for block 16 ofsuper-block 2, the block control field is encoded as “00000010” and isfollowed by sub-block 7.

Note that sub-block 7 indicates that one station, station 2 having anAID equal to 1010, is the only station for which the AP is buffering ormaintaining data. In other embodiments, the block control field forblock 16 of super-block 2 may include a bit to indicate that the bits ofsub-block 7 are inverted such that logical ones indicate that the AP isnot buffering data for the stations and logical zeros indicate that theAP is buffering data for the stations.

The inversion process may be applied for each block if, e.g., there aremore all-one values sub-blocks than all-zero values sub-blocks. In someembodiments, the first bit, b0, of the block control field such as blockcontrol field 1604 may be repurposed to be an inverse bit to indicatewhether the following sub-block bitmap fields are inversed or not. Inthe present embodiment, if the bit is set to 1, the sub-blocks areinversed. After inversion, only the sub-blocks with non-zero values areencoded in the corresponding block field. The bits, [b1 . . . b7] of theblock control field 1604 may be used to indicate whether sub-blocks arepresent or not in the block field. In such embodiments, if bit b0 isdefined as an inverse bit, the number of sub-blocks may be limited toseven and this may reduce the number stations that are supported in onepage (page ID) to four super-blocks by eight blocks by seven sub-blocksby eight stations, which may equal 1792. In other embodiments, adifferent bit may be defined for use as an inverse bit.

In the present embodiment, when the inverse bit is set to 1, thefollowing bits [b1 . . . b7] in the block control field are interpretedsuch that if bi is 0, insert i-th sub-block with the all-zero value. Onthe other hand, if bi is 1, use the received sub-block forreconstructing the block field and then inverse the reconstructed blockfield.

Referring again to FIG. 1G, the sub-block bitmap fields 1 1608 through N1610, if present, may be variable in length, e.g., 1 to 8 octets,depending on the value of the block control field 1604. Each bitcorresponds to an AID of a station. If the p-th bit of a sub-blockbitmap field is set to 1, it indicates that there is data buffered forthe corresponding station. Referring again to the embodiment 1800 inFIG. 1H, the sub-block 1 bitmap [b0 . . . b7] is encoded as “00000010”by setting the 6-th bit to 1. Setting the 6-th bit to 1 indicates thatthere is data buffered at the AP for the station 6. The sub-block 3bitmap [b0 . . . b7] is encoded as “00001000”.

Referring again to FIG. 1C, in many embodiments, the management frame1200 may comprise a frame check sequence (FCS) field 1226. The FCS field1226 may be four octets and may include extra checksum characters addedto the short frame 1060 for error detection and correction.

Note that the values shown in the FIGS. 1A-1H are for illustrativepurposes and may be other values in other embodiments.

FIG. 2 depicts an embodiment of an apparatus to generate, transmit,receive, and interpret or decode a traffic indication map (TIM) elementin a frame. The apparatus comprises a transceiver 200 coupled withMedium Access Control (MAC) sublayer logic 201 and a physical layer(PHY) logic 250. The MAC sublayer logic 201 may determine a frame andthe physical layer (PHY) logic 250 may determine the PPDU byencapsulating the frame or multiple frames, MAC protocol data units(MPDUs), with a preamble to transmit via transceiver 200.

In many embodiments, the MAC sublayer logic 201 may comprise a framebuilder 202 to generate frames such as one of the management frame 1200with TIM elements 1220 or 1300 illustrated in FIGS. 1A-H. The TIMelements may comprise data indicative of MAC service data units (MSDUs)buffered or stored by an associated access point (AP) for particularstations associated with the AP. Association identifiers (AIDs) mayidentify the stations. The AP such as the communications device 1010 anda station such as the communications device 1030 in FIG. 1 may maintainsome or part of the TIM elements 1220 or 1300 and values in memory suchas the memory 1012 and 1032 illustrated in FIG. 1.

The PHY logic 250 may comprise a data unit builder 203. The data unitbuilder 203 may determine a preamble to encapsulate the MPDU or morethan one MPDUs to generate a PPDU. In many embodiments, the data unitbuilder 203 may create the preamble based upon communications parameterschosen through interaction with a destination communications device.

The transceiver 200 comprises a receiver 204 and a transmitter 206. Thetransmitter 206 may comprise one or more of an encoder 208, a modulator210, an OFDM 212, and a DBF 214. The encoder 208 of transmitter 206receives and encodes data destined for transmission from the MACsublayer logic 202 with, e.g., a binary convolutional coding (BCC), alow density parity check coding (LDPC), and/or the like. The modulator210 may receive data from encoder 208 and may impress the received datablocks onto a sinusoid of a selected frequency via, e.g., mapping thedata blocks into a corresponding set of discrete amplitudes of thesinusoid, or a set of discrete phases of the sinusoid, or a set ofdiscrete frequency shifts relative to the frequency of the sinusoid. Theoutput of modulator 210 is fed to an orthogonal frequency divisionmultiplexer (OFDM) 212, which impresses the modulated data frommodulator 210 onto a plurality of orthogonal sub-carriers. And, theoutput of the OFDM 212 may be fed to the digital beam former (DBF) 214to form a plurality of spatial channels and steer each spatial channelindependently to maximize the signal power transmitted to and receivedfrom each of a plurality of user terminals.

The transceiver 200 may also comprise diplexers 216 connected to antennaarray 218. Thus, in this embodiment, a single antenna array is used forboth transmission and reception. When transmitting, the signal passesthrough diplexers 216 and drives the antenna with the up-convertedinformation-bearing signal. During transmission, the diplexers 216prevent the signals to be transmitted from entering receiver 204. Whenreceiving, information bearing signals received by the antenna arraypass through diplexers 216 to deliver the signal from the antenna arrayto receiver 204. The diplexers 216 then prevent the received signalsfrom entering transmitter 206. Thus, diplexers 216 operate as switchesto alternately connect the antenna array elements to the receiver 204and the transmitter 206.

The antenna array 218 radiates the information bearing signals into atime-varying, spatial distribution of electromagnetic energy that can bereceived by an antenna of a receiver. The receiver can then extract theinformation of the received signal.

The transceiver 200 may comprise a receiver 204 for receiving,demodulating, and decoding information bearing signals. The receiver 204may comprise one or more of a DBF 220, an OFDM 222, a demodulator 224and a decoder 226. The received signals are fed from antenna elements218 to a Digital Beam Former (DBF) 220. The DBF 220 transforms N antennasignals into L information signals. The output of the DBF 220 is fed tothe OFDM 222. The OFDM 222 extracts signal information from theplurality of subcarriers onto which information-bearing signals aremodulated. The demodulator 224 demodulates the received signal,extracting information content from the received signal to produce anun-demodulated information signal. And, the decoder 226 decodes thereceived data from the demodulator 224 and transmits the decodedinformation, the MPDU or more than one MPDUs, to the MAC sublayer logic201.

Persons of skill in the art will recognize that a transceiver maycomprise numerous additional functions not shown in FIG. 2 and that thereceiver 204 and transmitter 206 can be distinct devices rather thanbeing packaged as one transceiver. For instance, embodiments of atransceiver may comprise a Dynamic Random Access Memory (DRAM), areference oscillator, filtering circuitry, synchronization circuitry, aninterleaver and a deinterleaver, possibly multiple frequency conversionstages and multiple amplification stages, etc. Further, some of thefunctions shown in FIG. 2 may be integrated. For example, digital beamforming may be integrated with orthogonal frequency divisionmultiplexing.

The MAC sublayer logic 201 may decode or parse the MPDU or MPDUs todetermine the particular type of frame or frames and identify one ormore TIM elements included in the MPDU(s). For each TIM element, the MACsublayer logic 201 may parse the TIM element to determine the page IDfrom the TIM element. If the page ID matches the page ID for the MACsublayer logic 201 then the TIM element may comprise data related to thereceiving station associated with the MAC sublayer logic 201. The MACsublayer logic 201 may parse the TIM element to determine the superblock, the block, the sub-block, and the station within the sub-block,if present, that is associated with the AID for the receiving stationfrom the TIM element. If a bit associated with the receiving station isnot present or is a logical zero, then the receiving station may nothave data buffered at the AP. On the other hand, if the bit associatedwith the receiving station is present and is a logical one, thereceiving station may have data buffered at the AP.

In other embodiments, if an inverse bit is set in the TIM element, thepage ID may refer to the page or pages of the TIM that do not have databuffered, the super-blocks may refer to super-blocks that do not havedata buffered, the blocks may refer to blocks that do not have databuffered, the sub-blocks may refer to sub-blocks that do not have databuffered, or the bits associated with the AID of the receiving stationmay comprise a logical zero to indicate that data is buffered for thereceiving station at the AP and a logical one to indicate that data isnot buffered at the AP.

FIG. 3 depicts an embodiment of a flowchart 300 to generate or otherwisedetermine a management frame with a TIM element such as the TIM elementsdescribed in conjunction with FIGS. 1-2. The flowchart 300 begins with amedium access control (MAC) sublayer logic determining a MAC header fora management frame (element 305).

The MAC sublayer logic may thereafter determine the TIM element for theframe body. Determining the TIM element may comprise determining a pageidentifier field to identify the page of association identifiers (AIDs)for which the TIM element comprises information about data buffered forstations (element 310). For instance, the MAC sublayer logic may accessmemory to retrieve an element structure for the TIM elements and assignthe elements values such as a logical one to indicate that devices havedata buffered at the access point (AP) within which the MAC sublayerlogic resides.

The MAC sublayer logic may determine a super-block bitmap field (element315). The super-block bitmap field may identify one or more super-blockscomprising (AIDs) that indicate the AP buffers data. The MAC sublayerlogic may determine a block bitmap field (element 320). The block bitmapfield may be present for each of the super-blocks that indicate that theAP buffers data for associated stations. If, however, an inverse bit isdefined and set, the block bitmap field may be present for each of thesuper-blocks that indicate that the AP does not buffer data forassociated stations.

The MAC sublayer logic may determine a block control field (element325). The block control field may be present for each of the blocks thatindicate that the AP buffers data for associated stations. If, however,an inverse bit is defined and set, the block control field may bepresent for each of the blocks that indicate that the AP does not bufferdata for associated stations.

The MAC sublayer logic may determine a sub-block bitmap field (element330). The sub-block bitmap field may be present for each of thesub-blocks that indicate that the AP buffers data for associatedstations. If, however, an inverse bit is defined and set, the sub-blockbitmap field may be present for each of the sub-blocks that indicatethat the AP does not buffer data for associated stations.

If additional sub-blocks associated with the last block control fieldindicate that the AP buffers data for associated stations (element 335),the flowchart 300 continues by repeating element 330. Otherwise, if moreblocks associated with the super-blocks indicate that that the APbuffers data for associated stations, the flowchart 300 continues withelement 325 by determining another block control field.

Otherwise, the MAC sublayer logic may determine other elements of themanagement frame body frame (element 345). In many embodiments,determining the fields may comprise retrieving these fields from astorage medium for inclusion in a frame. In other embodiments, thevalues to include in such fields may be stored in a storage medium suchas a read only memory, random access memory, a cache, a buffer, aregister, or the like. In further embodiments, one or more of the fieldsmay be hardcoded into the MAC sublayer logic, PHY logic, or mayotherwise be available for insertion into a frame. In still otherembodiments, the MAC sublayer logic may generate the values of thefields based upon access to indications of the values for each.

After determining the other portions of the frame, the MAC sublayerlogic may determine a frame check sequence (FCS) field value (element350) to provide for error corrections in bit sequences received by thereceiving device.

FIGS. 4A-B depict embodiments of flowcharts 400 and 450 to transmit,receive, and interpret or decode communications with a management framewith a TIM element such as the TIM elements illustrated in FIGS. 1A-H.Referring to FIG. 4A, the flowchart 400 may begin with receiving a framefrom the frame builder comprising one or more TIM elements. The MACsublayer logic of the communications device may generate the frame as amanagement frame to transmit to a station and may pass the frame as anMPDU to a data unit builder that transforms the data into a packet thatcan be transmitted to a station. The data unit builder may generate apreamble to encapsulate one or more of the MPDUs from the frame builderto form a PPDU for transmission (element 405).

The PPDU may then be transmitted to the physical layer device such asthe transmitter 206 in FIG. 2 or the transceiver 1020,1040 in FIG. 1 sothe PPDU may be converted to a communication signal (element 410). Thetransmitter may then transmit the communication signal via the antenna(element 415).

Referring to FIG. 4B, the flowchart 450 begins with a receiver of astation such as the receiver 204 in FIG. 2 receiving a communicationsignal via one or more antenna(s) such as an antenna element of antennaarray 218 (element 455). The receiver may convert the communicationsignal into one or more MPDUs in accordance with the process describedin the preamble (element 460). More specifically, the received signal isfed from the one or more antennas to a DBF such as the DBF 220. The DBFtransforms the antenna signals into information signals. The output ofthe DBF is fed to OFDM such as the OFDM 222. The OFDM extracts signalinformation from the plurality of subcarriers onto whichinformation-bearing signals are modulated. Then, the demodulator such asthe demodulator 224 demodulates the signal information via, e.g., BPSK,16-QAM, 64-QAM, 256-QAM, QPSK, or SQPSK. And the decoder such as thedecoder 226 decodes the signal information from the demodulator via,e.g., BCC or LDPC, to extract the one or more MPDUs (element 460) andtransmits the one or more MPDUs to MAC sublayer logic such as MACsublayer logic 202 (element 465).

The MAC sublayer logic may decode the TIM element in each of the MPDUs.For instance, the MAC sublayer logic may parse the TIM element todetermine the value of the page ID field, one or more super-blockfields, the block bitmap field, a block control field for one or moreblocks, and the sub-block bitmap fields for one or more sub-blockbitmaps to determine whether the bit associated with the AID for thereceiving station indicates that the AP is buffering data for thestation (element 470). In some embodiments, the MAC sublayer logic maydetermine whether the other fields in the TIM element(s) indicate thatthe data will be broadcast to a group of devices after receipt of thebeacon comprising the TIM element, or if the AP will await a frame fromthe station instructing the AP to send the frame.

FIG. 5 depicts an embodiment of a flowchart 500 for a receiving stationto decode or otherwise determine information from a management framewith a TIM element such as the TIM elements described in conjunctionwith FIGS. 1-4. The flowchart 500 begins with a medium access control(MAC) sublayer logic receiving the TIM element (element 505). The MACsublayer logic may parse the TIM element to determine a page identifierto identify the page of association identifiers (AIDs) for which the TIMelement comprises information about data buffered for stations (element510). For instance, the MAC sublayer logic may access memory to retrievean association identifier (AID) assigned to the receiving station by theAP and parse the AID to determine the page ID associated with thereceiving station. If the page ID does not match the page ID determinedfrom the TIM element (element 515), then the receiving station may stopprocessing the TIM element (element 565).

If the page ID does match, the MAC sublayer logic may parse the TIMelement to determine the one or more super-blocks included in the TIMelement to identify the super-blocks of AIDs for which the TIM elementcomprises information about data buffered for stations (element 520). Ifthe super-block associated with the receiving station does not match thesuper-blocks determined from the TIM element (element 525), then thereceiving station may stop processing the TIM element (element 565).

If the super-block associated with the receiving station does match, theMAC sublayer logic may parse the TIM element to determine the one ormore blocks included in the TIM element to identify the blocks of AIDsfor which the TIM element comprises information about data buffered forstations (element 530). If the block associated with the receivingstation does not match the blocks determined from the TIM element(element 535), then the receiving station may stop processing the TIMelement (element 565).

If the block associated with the receiving station does match, the MACsublayer logic may parse the TIM element to determine the one or moreblock fields included in the TIM element to identify the blocks of AIDsfor which the TIM element comprises information about data buffered forstations (element 540). If the block associated with the receivingstation does not fall within the blocks identified in the block fieldsdetermined from the TIM element (element 545), then the receivingstation may stop processing the TIM element (element 565).

In some embodiments, the block fields may define an inverse bit thatinverses the indication of blocks or sub-blocks included in the TIMelement. If the inverse bit is defined for the embodiment and theinverse bit is set, then the MAC sublayer logic may determine whetherthe block within which the receiving stations AID resides is notincluded to determine whether the AP is buffering data for the receivingstation. In such embodiments, if the block is not included, thereceiving station may retrieve the data from the access point (element560).

Otherwise, the MAC sublayer logic may parse the TIM element to determinethe one or more sub-blocks included in the TIM element to identify thesub-blocks of AIDs for which the TIM element comprises information aboutdata buffered for stations (element 530). If the sub-block associatedwith the receiving station does not fall within the sub-blocksidentified in the sub-blocks determined from the TIM element (element555), then the receiving station may stop processing the TIM element(element 565).

If the sub-block associated with the receiving station does fall withinthe sub-blocks identified in the sub-blocks determined from the TIMelement (element 555), then the receiving station may retrieve the datafrom the access point (element 560).

Another embodiment is implemented as a program product for implementingsystems and methods described with reference to FIGS. 1-5. Someembodiments can take the form of an entirely hardware embodiment, anentirely software embodiment, or an embodiment containing both hardwareand software elements. One embodiment is implemented in software, whichincludes but is not limited to firmware, resident software, microcode,etc.

Furthermore, embodiments can take the form of a computer program product(or machine-accessible product) accessible from a computer-usable orcomputer-readable medium providing program code for use by or inconnection with a computer or any instruction execution system. For thepurposes of this description, a computer-usable or computer readablemedium can be any apparatus that can contain, store, communicate,propagate, or transport the program for use by or in connection with theinstruction execution system, apparatus, or device.

The medium can be an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system (or apparatus or device). Examples ofa computer-readable medium include a semiconductor or solid-statememory, magnetic tape, a removable computer diskette, a random accessmemory (RAM), a read-only memory (ROM), a rigid magnetic disk, and anoptical disk. Current examples of optical disks include compactdisk-read only memory (CD-ROM), compact disk-read/write (CD-R/W), andDVD.

A data processing system suitable for storing and/or executing programcode will include at least one processor coupled directly or indirectlyto memory elements through a system bus. The memory elements can includelocal memory employed during actual execution of the program code, bulkstorage, and cache memories which provide temporary storage of at leastsome program code in order to reduce the number of times code must beretrieved from bulk storage during execution.

The logic as described above may be part of the design for an integratedcircuit chip. The chip design is created in a graphical computerprogramming language, and stored in a computer storage medium (such as adisk, tape, physical hard drive, or virtual hard drive such as in astorage access network). If the designer does not fabricate chips or thephotolithographic masks used to fabricate chips, the designer transmitsthe resulting design by physical means (e.g., by providing a copy of thestorage medium storing the design) or electronically (e.g., through theInternet) to such entities, directly or indirectly. The stored design isthen converted into the appropriate format (e.g., GDSII) for thefabrication.

The resulting integrated circuit chips can be distributed by thefabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case, the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case, the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product.

It will be apparent to those skilled in the art having the benefit ofthis disclosure that the present disclosure contemplates methods andarrangements for traffic indication mapping for wireless communications.It is understood that the form of the embodiments shown and described inthe detailed description and the drawings are to be taken merely asexamples. It is intended that the following claims be interpretedbroadly to embrace all variations of the example embodiments disclosed.

What is claimed is:
 1. A device for wireless communications, the devicecomprising: a memory and a medium access control (MAC) logic coupled tothe memory, the memory and MAC logic configured to generate a framecomprising a traffic indication map (TIM), the TIM to include a partialvirtual bitmap field, wherein the partial virtual bitmap field is tocomprise multiple block fields; wherein each of the multiple blockfields is to comprise a block control subfield for a block of a trafficindication virtual bitmap, and encoded block information; wherein theblock control subfield is to comprise an inverse bit, wherein if theinverse bit is set to one, the bits of the block are to be inverted andthe block is to be encoded based on the inverted bits.
 2. The device ofclaim 1, wherein the block field is to comprise bits to indicate ifassociated subblocks are present in the block field; wherein a first bitis to be indicative of whether a first subblock is present in the blockfield.
 3. The device of claim 1, wherein each of the bits of the trafficindication virtual bitmap is to be associated with an associationidentifier (AID) for a station.
 4. The device of claim 1, further tocomprise a physical layer (PHY) logic coupled to the MAC logic, atransceiver coupled to the PHY logic, and one or more antennas coupledto the transceiver to transmit the frame and a preamble.
 5. The deviceof claim 4, wherein the memory, MAC logic, PHY logic, transceiver, andantenna are configured to transmit the frame to multiple other wirelessdevices.
 6. The device of claim 4, wherein the device is to transmit ina frequency band of less than 1 GHz.
 7. A method of wirelesscommunication, the method comprising: generating a frame comprising atraffic indication map (TIM), the TIM including a partial virtual bitmapfield, wherein the partial virtual bitmap field comprises multiple blockfields; wherein each of the multiple block fields comprises a blockcontrol subfield for a block of a traffic indication virtual bitmap, andencoded block information; wherein the block control subfield is tocomprise an inverse bit, wherein if the inverse bit is set to one, thebits of the block are to be inverted and the block is to be encodedbased on the inverted bits.
 8. The method of claim 7, wherein the blockfield comprises bits to indicate if associated subblocks are present inthe block field; wherein a first bit is indicative of whether a firstsubblock is present in the block field.
 9. The method of claim 7,wherein each of the bits of the traffic indication virtual bitmap isassociated with an association identifier (AID) for a station.
 10. Themethod of claim 7, further comprising transmitting the frame to multiplewireless devices.
 11. The method of claim 10, wherein said transmittingcomprises transmitting in a frequency band of less than 1 GHz.
 12. Acomputer-readable non-transitory storage medium that containsinstructions, which when executed by one or more processors result inperforming operations comprising: generating a frame comprising atraffic indication map (TIM), the TIM including a partial virtual bitmapfield, wherein the partial virtual bitmap field comprises multiple blockfields; wherein each of the multiple block fields comprises a blockcontrol subfield for a block of a traffic indication virtual bitmap, andencoded block information; wherein the block control subfield is tocomprise an inverse bit, wherein if the inverse bit is set to one, thebits of the block are to be inverted and the block is to be encodedbased on the inverted bits.
 13. The medium of claim 12, wherein theblock field comprises bits to indicate if associated subblocks arepresent in the block field; wherein a first bit is indicative of whethera first subblock is present in the block field.
 14. The medium of claim12, wherein each of the bits of the traffic indication virtual bitmap isassociated with an association identifier (AID) for a station.
 15. Themedium of claim 12, further comprising transmitting the frame tomultiple wireless devices.
 16. The medium of claim 15, wherein saidtransmitting comprises transmitting in a frequency band of less than 1GHz.